Dock Lines - The Proper Size and Placement for Your Boat

Thanks to Captain Frank Lecardo, Owner & Instructor, Naples School of Boating, for submitting this article. The Naples School of Boating specializes in providing on-water training for new and inexperienced boaters and those who want to enhance their existing skills.

Some of the most essential items aboard your boat are dock lines, and unfortunately, they are often overlooked considerations. This post will explore the different types of dock lines available and how to choose the right ones for your boat based on their intended use.

A primary consideration factor when choosing a dock line is the duration of its use. Is it being used on your permanent dock or as a temporary line when tying up at a restaurant, transient dock, or another brief scenario where you will be docked only briefly?

Permanent Dock Lines Considerations

Your permanent lines should always be the strongest and highest quality line that will fit on your cleats. They will last longer and provide you with maximum peace of mind when a storm hits. Also, your permanent dock lines should be protected against chafe. Chafing occurs when your dock lines continually rub against a surface that causes the lines to wear or deteriorate.

Types of Dock Lines

There are two basic types of dock lines for you to choose from:

• Three-strand Dock Line is the most basic and most affordable choice and ideal for temporary or transient dock lines that you carry onboard your boat.

• Double-braid Dock Line—is stronger, has less stretch than three-strand line, and is available in a wide assortment of colors to match your boat.

Whether you choose three-strand or double-braid, choose nylon lines because they are stronger and have more elasticity. Elasticity is an important consideration, as it helps absorb shocks when wind and waves cause abrupt movement of your boat.

Recommended Dock Line Diameter

Logically, larger boats require a larger diameter dock line. The chart below provides a handy guide.

Boat Length	Up to 27'	28'-31'	32'-36'	37'-45'	46'-54'	55'-63'	64'-72'
Dock Line Diameter	3/8"	7/16"	1/2"	5/8"	3/4"	7/8"	1"

Quick Glossary of Terms

To ensure our dock line placement information is clear, we've included the definitions of three critically important terms—bow line, stern line, and spring line.

Bow Line

The bow line runs from a cleat or chock and over the forward gunwale, where the line should be fitted with a chafe guard.

Stern Line

The stern line is attached to the stern tying fixture that is closest to the dock.

Spring Lines

There are two types of spring lines: forward springs and aft springs. The name of a spring line refers to which direction it is traveling when leaving the boat. A forward spring travels from the stern forward from one-half to one-third of the vessel length before being secured to the dock.

On the other hand, an aft spring line travels from the bow or forward gunwale back to the dock with a length about half the vessel's length.

Dock Line Placement

Bow and Stern Lines

Keep the boat parallel to the dock and prevent it from drifting outward away from the dock.

Spring Lines

Prevent the boat from drifting forward or aft and, coupled with the bow and stern lines, keep the boat in its desired location.

Preventing Chafe

Chafe is caused by the continual rubbing of lines against surfaces such as chocks and cleats or against pilings and docks that your boat is moored to. While chafing cannot be completely prevented, it can be greatly reduced by using chafe guards in critical positions.

Where should you place chafe guards? Place them wherever dock line will rub against chocks, cleats, docks, pilings, or other dock lines.